Exciting news from Heath @SakeBomb Garage on youtube above. Gotta give these some serious consideration for my next build.


The Specs: Stainless Steel Hot Side: Built to handle the extreme EGTs only a rotary can produce. External Wastegate Porting: Precision boost control for those chasing the perfect power curve.
https://sakebombgarage.com/eta-june-...el-twin-turbo/

 

I thought it would be more than 4k. They look promising for those still wanting to maintain twins. I don't know if I am a full believer that all of the cracking issues will be gone. Stainless steel is still able to crack. No matter what this will be better than old used, cracked equipment. Excited to see somebody put a bigger BNR kit with the stainless components.

 

Unfortunately, I am probably tapped out on putting even more into my build. I've got a new set of Stage 2 BNRs ready to go and I am interested in the larger wastegate porting, but I cant justify thr $3K just to get the housings (my BNRs have new OEM housings as-is) for questionable gains.

Maybe if I thought there was 50whp here, I'd do it. But, right now, there isn't even any evidence they have even ran these at all. Right now all they are claiming is they are confident their system can handle stock boost levels. And I get they have to be conservative, but I need something more than that to make me feel better about throwing $3K at their hot side.

Plus the last thing I need right now is another excuse to delay getting everything back together. And "June/July" is SBG-speak for Q4 at best.

 

I'm super excited about this. We have been long overdue for something like this. I'm glad somebody that was able to stepped it up because our manifolds are getting harder to find in good condition. I was eyeing the SP twins but can't wait to see what these do with the different configurations.

 

Very cool that they're collabing with BNR on this one. The twins will always be plagued by properly working solenoids however. A guy on eBay - Jimmy in Pensacola made an industrial solenoid kit that moved them out from under the intake manifold and was a permanent fix to any solenoid related sequential activation problems. Unfortunately they were super expensive, hopefully someone can find a fix/better solution. Heath should add those to his kit too for a bulletproof sequential solution.

 

I've thought about taking on this task in the future. When you replace the solenoids with new ones, they tend to last a long time, but they don't do as well under higher boost conditions, so they aren't for the people that want to add a lot more power via boost with sequentials. The problem isn't necessarily the solenoids, is the age of these cars, we can't expect old rubber hoses that sit in an oven essentially to last 30 years and be angry when they break.

 

I actually have a set of those solenoids that I bought back in the day.
They are lost in a box somewhere. I can't really use them here in CA with the visual inspection for smog...

 

I hadn't heard of these "industrial" solenoids. I did buy all new solenoids for my build. But, might be interested if you find them in the near future.

 

The original thread is linked in the FAQ thread: https://www.rx7club.com/3rd-generati...system-404243/

 

I think it's amazing these got made. Hat's off to SBG for the ambition and actually bringing it to market. If my car was still twin turbo, i'd have them. Great for CA guys or anyone who needs the car to look stock.

It would be even more interesting if they are or could be higher flowing and could get larger ball bearing turbos.

 

The only downside is that it costs almost twice as much as a Greddy single turbo kit.

 

Scanning through this thread that I linked below, it seems that the turbine wheel or more specifically, the hotside manifold which Sakebomb created from scratch is the main draw back of fitting bigger CHRA's since you are limited with the stock manifold but with Sakebomb capable of making these from scratch, maybe in the future they can address that and make version 2 of their stainless steal design that addresses this issue. It would be a big task since I'm sure this is for a mechanical engineer of some sort, which I'm sure there is plenty here that could tackle this project and help.

Here are some specs from "The Doctor", our favorite aussie.

 

Although, The Doctor doesn't think it's the turbine housing. Does anyone know what's the biggest restriction of the twins?

 

Rumors says that there will be BNR Stage 2 support at some point. For me they are pretty nice since i had landed on keeping the twins

 

Only need boring bar or cutter on the lathe or end mill and rotary table on a mill to prep the housings for bigger turbines.

 

For those that want to stay with the twins I'm glad to see support.... looks like a great step-up vs the older crack prone housings.


Steve

 

These are the industrial solenoids mentioned above. I was considering going the Efr route but may entertainment the SBG twins

 

What's the current draw on those? Wouldn't want to cook output drivers over time.

 

I wonder if there is much data on the Stage 2's, I haven't been able to find many reviews, dynos, logs etc. for people running the newer version of the BnR stages and mainly just information about the old Stage 3's. I'm curious to see the specs and potential of the stage 2's because this new revival of the twins is definitely in my future.

 

good on Sakebomb, it looks like a really nice piece and will be a welcome fit for those who want to retain the OE turbo system.

while the FD stands alone as to delivering road racing efficacy in a street package, the OE turbo system was the single most unfortunate choice in the build. they already had a wonderful template w the T2. i put over 200,000 happy miles on mine.

most of us are painfully familiar w the rats nest and the one way doors and solenoids. looks great on paper until you realize all the components are operating in an oven.

of course all of that can be work arounded. Penske won the 71 TransAm in a Javelin.

now that the system, thanks to SakeBomb, is a go for the future i want some data. as the market weighs either upgrading to the SB SS option versus going single my greatest interest lies in exhaust backpressure. it is no accident that most of the OE manifolds show large cracks at the exhaust port. there is nothing wrong w cast iron as a turbo manifold IF it is free flowing. no stress, no cracks. constriction = cracks.

one of the unalterable aspects of the system is that the two turbos exiting exhaust flow oppose each other. (?) Borg Warner talks about exhaust flow thru the turbo in terms of Mach. picture two garden hoses pointing at each other. this all happens in a plenum and the exit is on the side?

cracked cast iron is no surprise.

so what, you say? our motors, even w stock ports, have significant overlap both on the primary and secondary ports. if you have constricted exhaust flow/exhaust back pressure, you get backup into the pristine intake charge air... polluted intake air raises misfires and move the overall intake charge air closer to detonation.

i consider backpressure reduction to be the single most important reason to choose to go single.

as you raise flow using upgraded turbos you raise backpressure. perhaps SB was able to improve this metric. if i were them marketing this product i would log backpressure in the OE system and the new system. this could be a major positive to potential buyers who want to keep the legacy type of turbo system.

i congratulate them for their efforts to maintain and improve our wonderful antique cars.

 

This would be great information to see. Hopefully somebody with the resources can do some testing. It does look like they improved on the flow characteristics but there is only so much you can do with the space you have and as you said two outlets being pointed directly at each other. This is also where a proper downpipe plays a key part IMO. If the manifold isn't restricting, the pre-cat or tiny front pipe is creating a restriction point.

I think we need to look at the twins as not "top tier" performance, but more of a nostalgic OEM+ solution for that Fun factor having pretty much instant torque at any RPM. No doubt an efficient single setup is better all around for a track car. Between the simplicity and heat management alone a single solves many problems. I feel like sequentials are great for under 400hp with the sweet spot being 350 which is still a really fast street car. I wouldn't want to build a sequential setup over 400 mainly for the reasons you discussed with the back pressure and the heat generated in that setup which is much easier to manage with a single setup. Right now I plan 100% to snag a set of these new turbos but holding out until I get my custom intercooler tested and finalize and hoping that they will be able to add other BnR stages to them because I would like to be in that 350hp sweet spot range without pushing the stockers to their limits. It would be nice if they offered the manifold and turbine housings in a thermal barrier coating as well. When the time comes, I'll do a dyno video review on them as well like I am doing with the rest of my parts.

 

Quote:
Originally Posted by Howard Coleman CPR
good on Sakebomb, it looks like a really nice piece and will be a welcome fit for those who want to retain the OE turbo system.

while the FD stands alone as to delivering road racing efficacy in a street package, the OE turbo system was the single most unfortunate choice in the build. they already had a wonderful template w the T2. i put over 200,000 happy miles on mine.

most of us are painfully familiar w the rats nest and the one way doors and solenoids. looks great on paper until you realize all the components are operating in an oven.

of course all of that can be work arounded. Penske won the 71 TransAm in a Javelin.

now that the system, thanks to SakeBomb, is a go for the future i want some data. as the market weighs either upgrading to the SB SS option versus going single my greatest interest lies in exhaust backpressure. it is no accident that most of the OE manifolds show large cracks at the exhaust port. there is nothing wrong w cast iron as a turbo manifold IF it is free flowing. no stress, no cracks. constriction = cracks.

one of the unalterable aspects of the system is that the two turbos exiting exhaust flow oppose each other. (?) Borg Warner talks about exhaust flow thru the turbo in terms of Mach. picture two garden hoses pointing at each other. this all happens in a plenum and the exit is on the side?

cracked cast iron is no surprise.

so what, you say? our motors, even w stock ports, have significant overlap both on the primary and secondary ports. if you have constricted exhaust flow/exhaust back pressure, you get backup into the pristine intake charge air... polluted intake air raises misfires and move the overall intake charge air closer to detonation.

i consider backpressure reduction to be the single most important reason to choose to go single.

as you raise flow using upgraded turbos you raise backpressure. perhaps SB was able to improve this metric. if i were them marketing this product i would log backpressure in the OE system and the new system. this could be a major positive to potential buyers who want to keep the legacy type of turbo system.

i congratulate them for their efforts to maintain and improve our wonderful antique cars.

This causes a great deal of turbulent flow. Like Howard said, two garden hoses facing each other. IMHO, there could be a fix that would greatly improve the flow from massive turbulence to more laminar flow. Simply, put in a center divider between the turbo exhausts that is shaped like a slope on both sides and points to the downpipe. The exhaust would now try to follow the curve right on out the downpipe flange. The turbulence would definitely decrease, and the flow would improve and be pointed in the right direction. This could either be molded in, if possible, or bolted in after the main manifold is made. Laminar flow is the key to any efficient fluid or air movement. The more laminar the flow, the higher the velocity and more volume can be moved out. That's why smooth 90-degree bends are way better than straight 90-degree turns on any pipe.
Mike

 

While that is true, post turbine flow is highly turbulent- not laminar flow. This but is why the dead headed flow isnt as bad as it otherwise would be.

Still, would be better flow separated with their own expansion chambers. To smooth that turbulent flow to laminar.

 

True. But in my opinion, two separate expansion chambers couldn't happen with the limited space available. The sloped divider would be more practical in the limited space. My older SMB bellow downpipe would then accept the two side by side more laminar streams as it is directed out through the 4", then 3 1/2" downpipe.
Mike

 

I’ve already tapped both runners of my exhaust manifold with 1/8" NPT fittings and will be running some back-to-back testing. I’ll report the data here once I have it.

I’m using my 99 Spec twins as the baseline/control, and I’ll also be doing dyno runs on a Dynojet in parallel with the sensor logging so I can capture full horsepower and torque curves at the same time.

I’m installing anEMAP (Exhaust Manifold Absolute Pressure / backpressure) sensor on the front runner (pre-turbo, primary side) using the FFE EMAP canister kit with the 5 bar absolute pressure sensor and stainless hardline, and an EGT probe on the rear runner. Note that both runners communicate internally through a balance port, so the pressure is very similar between the two sides. I’m still putting the more useful EMAP sensor on the front runner (the one connected to the primary turbo, which is active most of the time).

I’ll be logging everything live through my FC Master with the I/O Extender.

Once the baseline is done, I’ll also be testing the Sakebombgarage hot-side manifold with BNR CHRAs attached to it. I’ll compare the sensor data (EMAP + EGT) and dyno graphs between the two setups at 14 psi boost, keeping all other mods the same. It would be a true single-variable test if I bolted the stock 99 twins CHRAs onto the SakeBomb hot-side manifold, but that’s honestly a big pain in the ***, so I’ll be comparing two variables: the SakeBomb hot-side + BNRs versus the complete stock 99 Spec turbos.

Looking forward to finally getting some real pre-turbine backpressure numbers on the stock twins versus the SBG hot-side manifold for the community. I’m confident the pressure difference will show positive results, but the real smoking gun for people considering the SakeBomb kit is hard data and I’m glad to provide it.

For reference, I also have one of the best exhaust setups available: Knightsports twin downpipe, FEED twin catalytic converters, and FEED catback (Sonic AS-V). This should help eliminate exhaust restriction as a variable in the comparison.